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Co-processing Carbon Footprint: Post-Consumer Plastic Waste vs Conventional Coal in Cement Plants

Co-processing is one of the go-to solutions in the area of plastic waste treatment and reduction. Post-consumer plastic (PCP) waste can be used as an alternative raw material in industrial, resource-intensive processes such as cement and steel manufacturing. The rotary kiln in cement plants operate at temperatures above 1,000 degrees Centigrade allowing for a complete degradation of any fuel subjected to this process.

In the waste management hierarchy, co-processing is in the middle tiers. It is more environmentally friendly and more sustainable than incineration and landfilling but it is less preferred than reusing and recycling. Co-processing leaves no residues and emits less greenhouse gases.

In the Philippines, requirements on co-processing is provided by the Department of Environment and Natural Resources (DENR) through DENR Administrative Order No. 2010-06 Guidelines on the Use of Alternative Fuels and Raw Materials in Cement Kilns. This specifies the requirement on the standard and procedures on the use of alternative fuel and raw materials for clinker in cement production. DAO 2010-06 specifies that the co-processing facility must be equipped with a continuous emissions monitoring systems (CEMS) that measure particulates, NOx and SOx among others. This ensures that operations comply with environmental standards. Other countries such as India also allow but regulate and monitor co-processing through stringent limits and regular monitoring

PCX continues to seek out the most environmentally friendly and sustainable options to reduce plastic waste. Our operations ensure that our processing partners receive, handle, store and treat the PCPs in accordance with the conditions set forth in their respective Environmental Compliance Certificates (ECCs) and in accordance with all applicable laws and regulations such as, but not limited to:

● RA 8749 – Philippine Clean Air Act of 1999

● RA9003 – Ecological Solid Waste Management Act of 2000

● Philippine Environmental Impact Statement (EIS) System (PD1586)

● Department of Labor and Employment Department Order No. 16, series of 2001

(Amendments to Rule 1030 of the Occupational Health and Safety Standards)

Tracking Carbon Footprint on Co-processing

One of the direct impacts of co-processing with PCP is that it substitutes the use of coal in cement operations. Coal is a non-renewable resource and is mostly imported (approximately 75%) here in the Philippines from Australia and Indonesia[1]. Assessment of the carbon footprint between the conventional use of coal is compared to a direct substitution of PCP in the cement process. Emissions of carbon dioxide (CO2) were estimated from available references and may vary depending on the circumstances.

For this analysis, CO2 emissions were estimated for use of coal and plastics to produce 1 ton of cement. Estimates on the carbon footprint were done on a life cycle analysis – (1) from the mining of coal and the production of a plastic, (2) to the transport requirements to bring the each fuel type to a cement plant and finally (3) the use of each fuel in the cement production process.

For each ton of cement produced, at least 200kg of coal is needed[2] . This can be replaced by the same amount of plastics although this varies (it may be higher or lower) depending on the basis of the heating value or the specific design of the kiln used. For simplicity, a 1:1 substitution of plastic is used.

Higher carbon dioxide emissions are caused by the mining of coal and the transport of coal to the Philippines. The former is attributed to the methane released in the conduct of coal mining[3]. Furthermore, coal is a single-use resource whereas plastics can be recycled or upcycled. On the other hand, importing coal even from nearby Indonesia has a much higher carbon footprint than sourcing PCPs from nearby aggregators. Estimates on shipping were used for at least 2,800km from Indonesia to Manila, Philippines and carbon dioxide emissions were calculated[4] . Upon use at the co-processing plant[5] , the CO2 emissions are usually within 10% of each other’s estimate. Overall, most of the carbon offset by choosing PCPs is from the importation of coal from other countries.

This preliminary assessment is done for estimation only and conservative assumptions were used – there are many other variables to consider in more detailed analyses. PCX continues to review and update estimates as new and more specific information comes in.

Co-processing Today and the Future Prospects Greenhouse gas emissions are relatively in parity between coal and PCPs as fuel in current coprocessing operations and technologies are being developed to address CO2 capture in such processes. In the bigger picture, there is value in reducing the demand for coal (especially imported coal) in local industries, diverting plastic waste away from landfills and oceans and with programs like the Aling Tindera Waste-to-Cash Program, incorporating community engagement and sharing the benefits to marginalized sectors of society. PCX continues to take a holistic approach in our efforts to achieve and measure plastic neutrality.

With safeguards and monitoring in place, co-processing currently provides a scalable, viable and working option for waste management in the Philippines. PCX continues to diversify and assess various solutions that can meet our primary objective of reducing plastics that go into landfills and oceans. For example, a study conducted in Indonesia[6] looks into the viability and scalability of the following:

1. Plastic waste into asphalt mixture – improves stickiness of asphalt 2. Producing pellets (plastic seeds) – can be used to produce plastic bags 3. Producing fuel oil – recycling through a pyrolysis process (produce less harmful substances)

As the world’s plastic waste continues to pile, PCX is committed to scout for environmentally friendly technologies in the future while simultaneously monitoring the sustainability and compliance of the treatment processes we have today.

About PCX Plastic Credit Exchange (PCX) is a Philippine-based non-profit organization that partners with sustainability-conscious businesses around the globe to responsibly offset their plastic footprint, and reduce the flow of plastic waste into our landfills and nature.

PCX has built a wide ecosystem of collaborators that recover, process and recycle plastic waste, and continuously seeks out the most environmentally and sound solutions to plastic waste reduction. PCX supports environmental protection with programs that improve livelihoods and scale up social impact.

Visit this article on PCX's website here.


[2] World Coal Association: Other uses of coal.

[3] National Wildlife Federation. Issue Brief: Accounting for Carbon Pollution from Coal Mining on Federal Lands.

[4] OECD Observer – Sea fairer: Marine Transport and CO2 Emissions.

[5] Carbon dioxide reduction by increased utilization of waste derived fuels in the cement industry by Tokheim, 2007

[6] A Study of Plastic Waste Management in Indonesia Industries by Hidayat et al, 2019



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